This invention relates to splash coolants for high voltage-high power electrical equipment.
A transformer apparatus is known, including an enclosed electrical apparatus utilizing a relatively small amount of liquid fluorocarbon which is sprayed in a thin layer over the electrical windings to cool them by evaporation of the fluorocarbon, the fluorocarbon vapors constituting at least a part of the electrically insulating gas atmosphere. Such an apparatus is disclosed in U.S. Pat. No. 2,561,738.
Systems are known, including a non-condensable dielectric gas added to such systems as a padding gas to provide added electrical insulation at low temperatures, particularly when the transformer is first turned on or is restarted after the liquid has cooled. Such systems are disclosed in U.S. Pat. Nos. 3,444,308, 3,452,147, 3,023,263 and 3,243,495. In each of these prior art devices, the vaporizable liquid is circulated independently by a liquid pump or the like. As a result, at operating temperatures, the non-condensable gas will accumulate around the top of the apparatus and block the diffusion or migration of the vaporized liquid from the transformer coils to the casing walls. Various complex systems have been developed for removing the non-condensable gas from the system once operating temperatures are achieved, as by a separation plant in U.S. Pat. No. 3,243,495 and separate cooler units with associated structures in U.S. Pat. Nos. 3,444,308 and 3,452,147. Such systems unduly complicate the operation of the coolant systems and sometimes lower the casing wall surface area to which the vaporized liquid may quickly migrate and be condensed.
U.S. Pat. No. 3,417,814 discloses an electrical apparatus submerged in coolant liquids. Such submersion systems would be unsuitable for transformers and the like where high dielectric strength, and thus high electrical insulation, is required.